The present invention relates to improvements of frying pans, skillets, pots and other cooking containers made of metal.
Metal cooking containers conventionally sold on the market are known as products fabricated of single or multiple metals, or as products treated by coating fluorine resin on the cooking surface.
Typical as cooking containers of the single or multiple metals are frying pans, pots, pans and others made of iron, stainless steel, aluminum or cooper. When materials (food) to be cooked are heated, the container is in general coated on the surface with oils, fats as butters or moisture.
However, since the existing cooking containers are flat and smooth in the heating and cooking surface, while the oil, fat or moisture stay thereon, the food under cooking is not scorched and stuck on the surface, but when they vanish due to oxidation at high temperature, vaporization or absorption, the food in contact with the heated metal surface at the high temperature invites soon oxidized films or oxides (carbides), and scorched, baked and stuck to the cooking surface.
If the cooking container of the single or multiple metal is once scorched and stuck on the metal surface, oxidation, corrosion or damage are caused in such spots, and when again heating and cooking, the material under cooking is easily scorched and stuck there.
The aluminum cooking container is slowly worn and spoiled during repeatedly using, even if an alumite corrosion resistant treatment is made on the surface, and such treatment vanishes at last, and an aluminum as basic material is exposed. An aluminum content flows out during cooking, gets to the cooking materials, and it injures health by repeatedly ingesting it.
For making up for such defects, many kinds of products are exhibited on the market, which are treated with coatings of fluorine resin (Teflon) on the heating and cooking surface of metal cooking containers. However, in those cooking containers, fluorine resin itself has problems to health. Further, since the coating surface is a soft property, it becomes worn and disappears while a metallic spatula is often used, and the coating comes off and the material under cooking is stuck to.
The present inventor proposed, in Japanese Utility Model Publication No. 4-15141, a cooking container with less scorching and sticking which had a heating part of a dual structure formed with an air layer with an interior part thereof. Since this cooking container controls a space between an inner container and an outer container with a screw or the like so as to regulate a heat convection in the air layer, it is more or less complicated mechanically and expensive.